Recent experiments demonstrate the induction of long-range order in correlated electron systems via external perturbations, which calls for a better understanding of nonthermal ordered states and nonequilibrium symmetry breaking. Here, we reveal a mechanism based on entropy cooling and entropy trapping in a strongly correlated multiorbital system. We consider a two-orbital Hubbard model with Hund coupling and crystal-field splitting and show that in the vicinity of a spin-state transition, crystal-field quenches can induce an excitonic condensation at initial temperatures above the highest ordering temperature in equilibrium. We furthermore identify a dynamical phase transition in the evolution of the order parameter and show that such quenches can result in long-lived nonthermal excitonic condensates which have no analog in the equilibrium phase diagram.

中文翻译：

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自旋态跃迁附近的非热激子凝聚

最近的实验证明了通过外部扰动在相关电子系统中产生长程有序感应，这要求人们更好地理解非热有序态和非平衡对称性破坏。在这里，我们揭示了一种在高度相关的多轨道系统中基于熵冷却和熵捕获的机制。我们考虑了具有Hund耦合和晶体场分裂的两轨道Hubbard模型，并表明，在自旋态跃迁附近，晶体场淬灭可以在高于平衡状态的最高有序温度的初始温度下引起激子凝聚。